[UnaClocker]

Noob Friendly Tutorial:
First, watch the video:
http://www.youtube.com/watch?v=Ui26Ggca4yM&fmt=18

To make your OSX Leopard install thumb drive (must be 8gb or better):
You will need access to an Intel Mac (PPC Disk Utility is broken)

On a Mac, insert the thumb drive into a USB port. Insert the Leopard DVD.
Open Disk Utility
Click on the Leopard DVD on the left.
Then click New Disk Image from the icons at the top row of Disk Utility
Agree to the defaults and let it go.
When it's done, the top menu bar (top of the screen) click Images, click Scan for Restore, and find the image you just created. Let it scan the image.
When that is done, click on the thumb drive on the left, you want to click on it's partition, that's the one below where it says the brand and size of the drive.
On the right will appear a tab that says "Restore" Click that.
Source: Click Image, and find the DMG you just created.
For Destination, drag that partition from your thumb drive on the left to this opening.
Check the box for "Erase Destination", and click restore.
Your drive has to be at least 8gb. This should also work with USB hard drives and the like.
When that's done, your OSX drive should pop up it's own finder window. Close that, eject the drive.

To make the Type11 (Boot132) Boot drive (128mb or better):
You will need access to a Windows machine.

* Format the USB stick in the FAT32 format.
* Download Syslinux 3.63
* Expand that zipfile. In the win32 subdirectory there is an executable called syslinux.exe. At the command line, run syslinux -ma f: (assuming F: is the drive letter referring to your freshly formatted USB stick; replace with the correct one if necessary)
* Copy the contents of the Type11 ISO file (not the image itself) to the USB stick, taking care not to overwrite anything that syslinux put on the USB stick (it only placed one file on the stick)
* You now have a bootable Type11 (Boot132).

Insert the Leopard thumb drive into a USB slot on the right hand side of the Mini9, and insert the Boot132 thumb drive into a slot on the left. Turn on the machine, make sure USB Legacy is Enabled in the BIOS. Press 0 while booting to get the boot menu, choose USB Drive, you should see some SYSLINUX text zipping across the screen, when you get a prompt, hit enter. You'll proceed to boot up into the Leopard installer.

See the Type11 install method for the rest of the instructions.

[esquilax]

Yeah, chosing that choice will get you nowhere... you have to hit esc here and then either type 81 or 82 (try the other if the first one doesn't work). I had a lot more luck following the DellEFI Method:

how-to-install-mac-os-x-dellefi-method-t3925.html

Which is more or less a newer version of the Type11 guide and has USB install instructions, which is where I learned this step. The USB disk image is newer, too, so don't forget to download that and copy those files over to your boot stick before you get to this part.